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1.
Dev Genes Evol ; 229(5-6): 197-206, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31734771

RESUMO

The Chinese giant salamander Andrias davidianus is regarded as an ideal model for studying local adaptations, such as longevity, tolerance to starvation, and cutaneous respiration. Transcriptome analysis is useful for studying the large and complex genomes of amphibians. Based on the coding gene set of adult A. davidianus, dozens of A. davidianus-specific genes were identified and three signaling pathway (JAK-STAT, HIF-1, and FoxO) genes were expanded as compared with other amphibians. The results of the pathway analysis of A. davidianus-specific genes indicated that the molecular adaptation of A. davidianus may have required a more rapid evolution of the immune system. Additionally, for the first time, the gene expressions in different parts of the skin tissue were compared. The results of the comparison analysis demonstrated that lateral skin could be more focused on mucus secretion, dorsal skin on immunity and melanogenesis, and abdominal skin on water and salt metabolism. This study provides the first insight into studying longevity and starvation tolerance in A. davidianus, and offers a basis for further investigation of the molecular mechanisms of adaptations in amphibians.


Assuntos
Urodelos/genética , Urodelos/fisiologia , Adaptação Biológica , Animais , Evolução Biológica , China , Longevidade , Especificidade de Órgãos , Pele/metabolismo
2.
Nat Commun ; 10(1): 4091, 2019 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-31501425

RESUMO

Organisms rely upon external cues to avoid detrimental conditions during environmental change. Rapid water loss, or desiccation, is a universal threat for terrestrial plants and animals, especially under climate change, but the cues that facilitate plastic responses to avoid desiccation are unclear. We integrate acclimation experiments with gene expression analyses to identify the cues that regulate resistance to water loss at the physiological and regulatory level in a montane salamander (Plethodon metcalfi). Here we show that temperature is an important cue for developing a desiccation-resistant phenotype and might act as a reliable cue for organisms across the globe. Gene expression analyses consistently identify regulation of stem cell differentiation and embryonic development of vasculature. The temperature-sensitive blood vessel development suggests that salamanders regulate water loss through the regression and regeneration of capillary beds in the skin, indicating that tissue regeneration may be used for physiological purposes beyond replacing lost limbs.


Assuntos
Mudança Climática , Sinais (Psicologia) , Dessecação , Temperatura Ambiente , Urodelos/fisiologia , Animais , Vasos Sanguíneos/crescimento & desenvolvimento , Vasos Sanguíneos/metabolismo , Redes Reguladoras de Genes , Lipídeos/química , Neovascularização Fisiológica/genética , Fatores de Risco , Pele , Transcrição Genética , Transcriptoma/genética , Urodelos/genética
3.
Biochemistry (Mosc) ; 84(4): 380-389, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31228929

RESUMO

MicroRNAs (miRNAs), a family of ∼22-nucleotide non-coding single-stranded RNA molecules, are considered as key post-transcriptional regulators of gene expression that regulate various biological processes in living organism. Many miRNAs have been identified in animals; however, few have been reported in Hynobiidae species. The present study is aimed to identify a full repertoire of miRNAs in Batrachuperus yenyuanensis (Yenyuan stream salamander), which would significantly increase our knowledge of miRNAs in amphibians. A small RNA library was constructed from B. yenyuanensis and sequenced using deep sequencing. As a result, 1,717,751 clean reads were obtained, representing 356 known and 80 novel miRNAs. Additionally, expression levels of eight randomly selected miRNAs in B. yenyuanensis were confirmed using the stem-loop quantitative real-time reverse transcription PCR. In addition, 13,972 targets were predicted for these identified miRNAs, although the physiological functions of many of these targets remain unknown. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis suggested that the predicted targets are involved in a variety of physiological regulatory functions in B. yenyuanensis. These results provide useful information for further research on the miRNAs involved in the growth and development of B. yenyuanensis, as well as adaptation of this species to its high-altitude habitats.


Assuntos
MicroRNAs/metabolismo , Urodelos/genética , Animais , Sequência de Bases , Biblioteca Gênica , Ontologia Genética , Sequenciamento de Nucleotídeos em Larga Escala , Masculino , MicroRNAs/análise , MicroRNAs/química , Reação em Cadeia da Polimerase , Análise de Sequência de RNA , Testículo/metabolismo , Urodelos/metabolismo
4.
BMC Genomics ; 20(1): 482, 2019 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-31185901

RESUMO

BACKGROUND: Global biodiversity is decreasing at an alarming rate and amphibians are at the forefront of this crisis. Understanding the factors that negatively impact amphibian populations and effectively monitoring their health are fundamental to addressing this epidemic. Plasma glucocorticoids are often used to assess stress in amphibians and other vertebrates, but these hormones can be extremely dynamic and impractical to quantify in small organisms. Transcriptomic responses to stress hormones in amphibians have been largely limited to laboratory models, and there have been few studies on vertebrates that have evaluated the impact of multiple stressors on patterns of gene expression. Here we examined the gene expression patterns in tail tissues of stream-dwelling salamanders (Eurycea tynerensis) chronically exposed to the stress hormone corticosterone under different temperature regimes. RESULTS: We found unique transcriptional signatures for chronic corticosterone exposure that were independent of temperature variation. Several of the corticosterone responsive genes are known to be involved in immune system response (LY-6E), oxidative stress (GSTM2 and TRX), and tissue repair (A2M and FX). We also found many genes to be influenced by temperature (CIRBP, HSC71, HSP40, HSP90, HSP70, ZNF593). Furthermore, the expression patterns of some genes (GSTM2, LY-6E, UMOD, ZNF593, CIRBP, HSP90) show interactive effects of temperature and corticosterone exposure, compared to each treatment alone. Through a series of experiments we also showed that stressor induced patterns of expression were largely consistent across ages, life cycle modes, and tissue regeneration. CONCLUSIONS: Outside of thermal stressors, the application of transcriptomes to monitor the health of non-human vertebrate systems has been vastly underinvestigated. Our study suggests that transcriptomic patterns harbor stressor specific signatures that can be highly informative for monitoring the diverse stressors of amphibian populations.


Assuntos
Perfilação da Expressão Gênica , Estresse Fisiológico/genética , Urodelos/genética , Urodelos/fisiologia , Animais , Corticosterona/farmacologia , Estágios do Ciclo de Vida/efeitos dos fármacos , Estágios do Ciclo de Vida/genética , Temperatura Ambiente , Transcrição Genética/efeitos dos fármacos , Urodelos/crescimento & desenvolvimento
5.
Genome ; 62(8): 549-561, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31172800

RESUMO

Unisexual Ambystoma are the oldest known unisexual vertebrates and comprise a lineage of eastern North American all female salamanders that reproduce by stealing sperm from as many as five normally bisexual congeneric species. The sperm may be used to only stimulate egg development by gynogenesis but can be incorporated in the zygote to elevate the ploidy level or to replace one of the female's haploid genomes. This flexible and unique reproductive system, termed kleptogenesis, is investigated using a microsatellite examination of 988 offspring from 14 unisexual mothers. All mothers produced clonal and ploidy-elevated offspring. Genome replacement and multiple paternity are confirmed for the first time in unisexual Ambystoma. Microsatellite mutations were found in all five microsatellite loci and the estimated microsatellite mutation rate varied by locus and by genome. Clonal variation is attributed to the inclusion of sperm donors' haploid genomes for ploidy elevation, genome replacement, mutations, and natural selection.


Assuntos
Taxa de Mutação , Reprodução/genética , Urodelos/genética , Animais , Feminino , Repetições de Microssatélites , Ploidias , Urodelos/fisiologia
6.
BMC Genomics ; 20(1): 415, 2019 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-31122206

RESUMO

BACKGROUND: Chinese giant salamander Andrias davidianus is an endangered species. The success of artificial breeding provides a useful way to protect this species. However, the method to identify the sex and mechanism of sex determination were unclear which hinder the improvement of the artificial breeding. Detection of a sex specific marker provides an effective approach to identify genetic sex and investigate the sex determination mechanism. RESULTS: We used restriction-site-associated DNA (RAD) sequencing to isolate a sex-specific genetic marker in A. davidianus to expand knowledge of the sex determination mechanism. Four male and four female specimens were subjected to RAD sequencing, which generated 934,072,989 reads containing approximately 134.4 Gb of sequences. The first round of comparison of the assembled sequence against the opposite sex raw reads revealed 19,097 female and 17,994 male unmatched sequences. Subsequently, 19,097 female sequences were subjected to a BLAST search against male genomic data, which revealed 308 sequences unmapped to the male genome. One hundred of these were randomly selected and validated by PCR in five male and five female specimens, and four putative sex-specific sequences were produced. Further validation was performed by PCR in another 24 females and 24 males, and all female individuals exhibited the expected specific bands, while the males did not. To apply the sex-specific marker, three specimens reversed from genetic female to physiological male were found in a group exposed to elevated temperature, and 13 individuals reversed from genetic male to physiological female were obtained in a 17ß-estradiol exposed group. CONCLUSION: This is the first report of a sex-specific marker in A. davidianus and may have potential for elucidation of its sex determination mechanism and, hence, its conservation.


Assuntos
Caracteres Sexuais , Urodelos/genética , Animais , Feminino , Marcadores Genéticos , Genoma , Masculino , Análise de Sequência de DNA
7.
PLoS One ; 14(5): e0216754, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31091252

RESUMO

BACKGROUND: Body shape can be both a consequence and cause of a species' evolution and ecology. There are many examples of phenotypes associated with specific ecological niches, likely as a result of specific selective regimes. A classic example of this is the phenotypic change associated with colonization of caves, including body and limb elongation. However, studies explicitly testing for differences in body shape between cave-dwelling and non-cave-dwelling lineages have been limited and so the role of the cave environment in determining morphological characteristics is still not completely understood. Here we examine variation in body shape among 405 individuals representing 20 species in the salamander genus Eurycea (Plethodontidae) and select outgroups exhibiting great diversity in morphology, ecological niche, and life history. RESULTS: After analyzing morphometric data in a phylogenetic context using phylogenetic MANOVA and examination of the phylomorphospace, we found significant differences in body shape among cave-dwelling and non-cave-dwelling species and between aquatic and terrestrial species. Notably, limb elongation and reduced body and tail size characterized cave-dwelling species. Terrestrial species also exhibited elongation of the limbs and digits. We also observed differences in shape variance among paedomorphic and biphasic species. Our results suggest that the functional limitations imposed by habitat and life history played a key role in the evolution of body shape in this group in the context of their phylogenetic history.


Assuntos
Urodelos/anatomia & histologia , Animais , Biodiversidade , Evolução Biológica , Tamanho Corporal , Cavernas , Ecossistema , Extremidades/anatomia & histologia , Fenótipo , Filogenia , Cauda/anatomia & histologia , Urodelos/classificação , Urodelos/genética
8.
Mol Phylogenet Evol ; 137: 138-145, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31085325

RESUMO

The lack of distinct morphological features of cryptic species is a hard problem for taxonomy, especially when the taxa are closely related with considerable amounts of ancestral polymorphism. Lately, intensive coalescent-based analyses involving multiple loci have become the preferred method to assess the extent of genetic distinctiveness in otherwise phenotypically similar populations. Previously, phylogenetic studies on Pachyhynobius shangchengensis uncovered five extremely deeply divergent clades, which suggested that this species may be a cryptic species complex. In this study, we used the complete mitochondrial genome data and samples from the entire range of stout salamander (Pachyhynobius), as well as publicly available mitochondrial genomes to assess species boundaries within this genus using a suite of diverse methodologies (e.g. general mixed Yule coalescent model, Automatic Barcode Gap Discovery). The phylogenetic relationships recovered two major groups within P. shangchengensis, with one group formed by four of the six extant populations and corresponding to the central and eastern range of the Dabie mountains, while the other group encompassed two other lineages in the north west of the Dabie mountain range. The species delimitation comparison within Pachyhynobius supported the presence of recognized species within the genus, and consensus was observed across methods for the existence of up to five cryptic species within what has been traditionally considered to be P. shangchengensis. While this implies the existence of four taxa in addition to the described P. shangchengensis species, morphological data and life history information are further required to contribute to the species definition. The observed pattern of genetic variation is likely the outcome of a discontinuous habitat combined with niche conservatism, which produced the sky-island effect observed in Pachyhynobius, and which led to formation of a hidden species diversity in this genus.


Assuntos
Biodiversidade , Genoma Mitocondrial , Urodelos/genética , Animais , China , Código de Barras de DNA Taxonômico , Geografia , Filogenia , Especificidade da Espécie
9.
Int J Mol Sci ; 20(7)2019 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-30934682

RESUMO

The Yenyuan stream salamander (Batrachuperus yenyuanensis) has been previously evaluated with regards to phylogeny, population genetics, and hematology, but genomic information is sparse due to the giant genome size of salamanders which contain highly repetitive sequences, thus resulting in the lack of a complete reference genome. This study evaluates the encoding genetic sequences and provides the first transcriptome assembly of Yenyuan stream salamander based on mixed samples from the liver, spermary, muscle and spleen tissues. Using this transcriptome assembly and available encoding sequences from other vertebrates, the gene families, phylogenetic status, and species divergence time were compared or estimated. A total of 13,750 encoding sequences were successfully obtained from the transcriptome assembly of Yenyuan stream salamander, estimated to contain 40.1% of the unigenes represented in tetrapod databases. A total of 88.79% of these genes could be annotated to a biological function by current databases. Through gene family clustering, we found multiple possible isoforms of the Scribble gene-whose function is related to regeneration-based on sequence similarity. Meanwhile, we constructed a robust phylogenetic tree based on 56 single-copy orthologues, which indicates that based on phylogenetic position, the Yenyuan stream salamander presents the closest relationship with the Chinese giant salamander (Andrias davidianus) of the investigated vertebrates. Based on the fossil-calibrated phylogeny, we estimated that the lineage divergence between the ancestral Yenyuan stream salamander and the Chinese giant salamander may have occurred during the Cretaceous period (~78.4 million years ago). In conclusion, this study not only provides a candidate gene that is valuable for exploring the remarkable capacity of regeneration in the future, but also gives an interesting insight into the understanding of Yenyuan stream salamander by this first transcriptome assembly.


Assuntos
Evolução Molecular , Transcriptoma/genética , Urodelos/genética , Animais , China , Geografia , Família Multigênica , Filogenia , Rios , Especificidade da Espécie , Fatores de Tempo
10.
Genes (Basel) ; 10(4)2019 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-31003559

RESUMO

The Hyrcanian Forests present a unique Tertiary relict ecosystem, covering the northern Elburz and Talysh Ranges (Iran, Azerbaijan), a poorly investigated, unique biodiversity hotspot with many cryptic species. Since the 1970s, two nominal species of Urodela, Hynobiidae, Batrachuperus (later: Paradactylodon) have been described: Paradactylodon persicus from northwestern and P. gorganensis from northeastern Iran. Although P. gorganensis has been involved in studies on phylogeny and development, there is little data on the phylogeography, systematics, and development of the genus throughout the Hyrcanian Forests; genome-wide resources have been entirely missing. Given the huge genome size of hynobiids, making whole genome sequencing hardly affordable, we aimed to publish the first transcriptomic resources for Paradactylodon from an embryo and a larva (9.17 Gb RNA sequences; assembled to 78,918 unigenes). We also listed 32 genes involved in vertebrate sexual development and sex determination. Photographic documentation of the development from egg sacs across several embryonal and larval stages until metamorphosis enabled, for the first time, comparison of the ontogeny with that of other hynobiids and new histological and transcriptomic insights into early gonads and timing of their differentiation. Transcriptomes from central Elburz, next-generation sequencing (NGS) libraries of archival DNA of topotypic P. persicus, and GenBank-sequences of eastern P. gorganensis allowed phylogenetic analysis with three mitochondrial genomes, supplemented by PCR-amplified mtDNA-fragments from 17 museum specimens, documenting <2% uncorrected intraspecific genetic distance. Our data suggest that these rare salamanders belong to a single species P. persicus s.l. Humankind has a great responsibility to protect this species and the unique biodiversity of the Hyrcanian Forest ecosystems.


Assuntos
Perfilação da Expressão Gênica/veterinária , Redes Reguladoras de Genes , Urodelos/crescimento & desenvolvimento , Sequenciamento Completo do Exoma/veterinária , Animais , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Sequenciamento de Nucleotídeos em Larga Escala/veterinária , Irã (Geográfico) , Masculino , Filogenia , Filogeografia , Processos de Determinação Sexual , Urodelos/classificação , Urodelos/genética
11.
Genetica ; 147(2): 149-164, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30879155

RESUMO

Land use changes are threatening the maintenance of biodiversity. Genetic diversity is one of the main indicators of biological diversity and is highly important as it shapes the capability of populations to respond to environmental changes. We studied eleven populations of Pseudoeurycea robertsi, a micro-endemic and critically endangered species from the Nevado de Toluca Volcano, a mountain that is part of the Trans-Mexican Volcanic Belt, Mexico. We sequenced the mitochondrial cytochrome b gene from 71 individuals and genotyped 9 microsatellites from 150 individuals. Our results based on the cytochrome b showed two divergent lineages, with moderate levels of genetic diversity and a recently historical demographic expansion. Microsatellite-based results indicated low levels of heterozygosity for all populations and few alleles per locus, as compared with other mole salamander species. We identified two genetically differentiated subpopulations with a significant level of genetic structure. These results provide fundamental data for the development of management plans and conservation efforts for this critically endangered species.


Assuntos
Espécies em Perigo de Extinção , Polimorfismo Genético , Urodelos/genética , Animais , Ecossistema , Repetições de Microssatélites
12.
Am Nat ; 193(4): 608-618, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30912974

RESUMO

Understanding polymorphism is a central problem in evolution and ecology, and alternative reproductive tactics (ARTs) provide compelling examples for studying the origin and maintenance of behavioral and morphological variation. Much attention has been given to examples where "parasitic" individuals exploit the reproductive investment of "bourgeois" individuals, but some ARTs are instead maintained by environmental heterogeneity, with alternative tactics exhibiting differential fitness in discontinuous reproductive niches. We use genomic, behavioral, karyological, and field observational data to demonstrate one such example in plethodontid salamanders. These ARTs ("searching" and "guarding" males) are associated with different reproductive niches and, unlike most other examples in amphibians, demonstrate substantial morphological differences and inflexibility within a reproductive season. Evidence suggests the existence of these ARTs within three putative species in the two-lined salamander (Eurycea bislineata) species complex, with other members of this clade fixed for one of the two tactics. We highlight directions for future research in this system, including the relationship between these ARTs and parental care.


Assuntos
Comportamento Sexual Animal , Urodelos/anatomia & histologia , Animais , Comportamento Apetitivo , Feminino , Cariótipo , Masculino , Comportamento de Nidação , Filogenia , Reprodução , Urodelos/genética
13.
BMC Evol Biol ; 19(1): 1, 2019 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-30606099

RESUMO

BACKGROUND: Climate oscillation may have a profound effect on species distributions, gene flow patterns and population demography. In response to environmental change, those species restricted to montane habitats experienced expansions and contractions along elevation gradients, which can drive differentiation among sky islands. RESULTS: The Shangcheng stout salamander (Pachyhynobius shangchengensis) is a cool stream amphibian restricted to high-elevation areas in the Dabie Mountains, East China. In the present study, we used mtDNA genes (Cyt b and ND2) of 193 individuals and 12 nuclear microsatellite loci genotyped on 370 individuals, representing 6 populations (JTX, KHJ, MW, TTZ, BYM and KJY) across the taxon's distribution area, to investigate their genetic variation and evolutionary history of P. shangchengensis. Most populations showed unusually high levels of genetic diversity. Phylogenetic analyses revealed five monophyletic clades with divergence times ranging from 3.96 to 1.4 Mya. Accordingly, significant genetic differentiation was present between these populations. Bayesian skyline plot analyses provided that all populations underwent long-term population expansions since the last inter-glacial (0.13 Mya ~ 0.12 Mya). Msvar analyses found recent signals of population decline for two northern populations (JTX and KHJ) reflecting a strong bottleneck (approximately 15-fold decrease) during the mid-Holocene (about 6000 years ago). Ecological niche modelling has shown a discontinuity in suitable habitats for P. shangchengensis under different historical climatic conditions. CONCLUSIONS: Our results suggest that the niche conservatism of P. shangchengensis and sky island effects may have led to long-term isolation between populations. In sky island refuges, the mid-latitude Dabie Mountains have provided a long-term stable environment for P. shangchengensis, which has led to the accumulation of genetic diversity and has promoted genetic divergence.


Assuntos
Variação Genética , Ilhas , Filogenia , Rios , Urodelos/classificação , Urodelos/genética , Animais , China , Análise por Conglomerados , DNA Mitocondrial/genética , Demografia , Ecossistema , Extremo Oriente , Genótipo , Repetições de Microssatélites/genética , Filogeografia
14.
Mol Genet Genomics ; 294(2): 287-299, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30377773

RESUMO

The Chinese giant salamander Andrias davidianus is a protected amphibian with high nutritional and economic value. Understanding its sex determination mechanism is important for improving culture techniques and sex control in breeding. However, little information on the characterization of critical genes involved in sex is available. Herein, sequencing of ovary and test produced 40,783,222 and 46,128,902 raw reads, respectively, which were jointly assembled into 80,497 unigenes. Of these, 36,609 unigenes were annotated, of which 8907 were female-biased and 10,385 were male-biased. Several sex-related pathways were observed, including the Wnt signaling pathway. After elevated temperature and estrogen exposure, neomale and neofemale specimens were identified by a female-specific marker for the first time. RT-qPCR analysis showed the expression profile of ten selected sex-biased genes to be exhibited consistently in male and neomale and in female and neofemale, with the exception of the Amh and TfIIIa genes. Results suggested that these genes may play important roles in A. davidianus sex determination and gonad development. This provides a basis for further investigation of the molecular mechanisms of sex determination in amphibians.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento/genética , Processos de Determinação Sexual , Transcriptoma/genética , Urodelos/genética , Animais , Feminino , Gônadas/crescimento & desenvolvimento , Sequenciamento de Nucleotídeos em Larga Escala , Masculino , Anotação de Sequência Molecular , Ovário/crescimento & desenvolvimento , Urodelos/crescimento & desenvolvimento
15.
J Evol Biol ; 32(3): 278-286, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30588701

RESUMO

Salamanders (Urodela) have among the largest vertebrate genomes, ranging in size from 10 to 120 pg. Although changes in genome size often occur randomly and in the absence of selection pressure, nonrandom patterns of genome size variation are evident among specific vertebrate lineages. Several reports suggest a relationship between species richness and genome size, but the exact nature of that relationship remains unclear both within and across different taxonomic groups. Here, we report (a) a negative relationship between haploid genome size (C-value) and species richness at the family taxonomic level in salamander clades; (b) a correlation of C-value and species richness with clade crown age but not with diversification rates; (c) strong associations between C-value and both geographic area and climatic-niche rate. Finally, we report a relationship between C-value diversity and species diversity at both the family- and genus-level clades in urodeles.


Assuntos
Especiação Genética , Tamanho do Genoma , Filogenia , Urodelos/genética , Animais , Biodiversidade , Tamanho Corporal , Feminino , Masculino , Urodelos/anatomia & histologia
16.
Gene ; 690: 68-74, 2019 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-30583027

RESUMO

Bichirs are a sister group to sarcopterygian and tetrapods that can fully regenerate their endochondral-skeleton-fins. Histological and transcriptomic comparison approaches have been used to investigate the morphology and genetic basis of bichir lobe-fin regeneration, with strong down-regulation of muscle-related genes and up-regulation of ECM-related genes and developmental genes being observed. Bichir limb regeneration involves similar cellular processes to those employed by lungfish and salamander, with MARCKS-like protein (MLP) that is known to be a putative regeneration-initiating molecule in salamander, also up-regulated in the early stages of bichir lobe-fin regeneration. These gene expression results suggest that limb regeneration pathways in these amphibians have a common ancestral inheritance, consistent with evolution from endochondral-skeleton-fin structures to endochondral-skeleton-limb structures of vertebrates.


Assuntos
Peixes/fisiologia , Perfilação da Expressão Gênica/métodos , Redes Reguladoras de Genes , Urodelos/fisiologia , Nadadeiras de Animais/fisiologia , Animais , Evolução Biológica , Proteínas de Peixes/genética , Peixes/genética , Regulação da Expressão Gênica no Desenvolvimento , Filogenia , Regeneração , Análise de Sequência de RNA/métodos , Urodelos/genética
17.
PLoS One ; 13(12): e0207460, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30517124

RESUMO

The salamander family Sirenidae is represented by four extant species that are restricted to North America. Sirens are abundant throughout the southern United States and are among the world's largest amphibians, yet the biology, ecology, and phylogeography of this group is poorly-known. In this study we use morphological and genetic evidence to describe a previously unrecognized species from southern Alabama and the Florida panhandle. We name this species the Reticulated Siren, Siren reticulata. Future studies will enable more precise phylogenetic information about S. reticulata and will almost surely reveal additional undescribed species within the family.


Assuntos
Especiação Genética , Urodelos/genética , Alabama , Anfíbios , Animais , Florida , Filogenia , Filogeografia , Estados Unidos
18.
Sci Rep ; 8(1): 16507, 2018 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-30405202

RESUMO

The so-called glacial refugia, formed during the Pleistocene climatic oscillations, played a major role in shaping the distribution of European species, triggering migrations or isolating populations. Many of these events were recently investigated by genetic data, mainly for the European Last Glacial stage, in the Iberic, Italian and Greek-Balkan peninsulas. The amphibian genus Salamandrina, the most ancient living salamandrid lineage, was widespread in Europe until the climatic oscillations of Miocene probably forced it to shelter in the only suitable territory at that time, the Apennines. Nowadays this genus is endemic of peninsular Italy with two parapatric species, S. perspicillata and S. terdigitata, sharing an area of secondary contact formed after the Last Glacial Maximum. Climate is generally identified as the key factor for the interpretation of genetic data. In this research, we directly measure climate influences on the two Salamandrina known species through Ensemble Modelling techniques and post-modelling GIS analyses, integrating updated genetic data in this process. Our results confirm the hypotheses of southwards (and subsequent northwards) shifts, identify glacial refugia and corridors used for the post-glacial re-colonization. Finally, we map a contact zone deserving more sampling effort to disentangle the introgression and hybridization observed.


Assuntos
Clima , Interação Gene-Ambiente , Aptidão Genética , Genética Populacional , Haplótipos , Urodelos/genética , Animais , Evolução Biológica , Bases de Dados Factuais , Variação Genética , Geografia , Modelos Teóricos
19.
Proc Biol Sci ; 285(1888)2018 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-30282653

RESUMO

Numerous physiological and morphological adaptations were achieved during the transition to lungless respiration that accompanied evolutionary lung loss in plethodontid salamanders, including those that enable efficient gas exchange across extrapulmonary tissue. However, the molecular basis of these adaptations is unknown. Here, we show that lungless salamanders express in the larval integument and the adult buccopharynx-principal sites of respiratory gas exchange in these species-a novel paralogue of the gene surfactant-associated protein C (SFTPC), which is a critical component of pulmonary surfactant expressed exclusively in the lung in other vertebrates. The paralogous gene appears to be found only in salamanders, but, similar to SFTPC, in lunged salamanders it is expressed only in the lung. This heterotopic gene expression, combined with predictions from structural modelling and respiratory tissue ultrastructure, suggests that lungless salamanders may produce pulmonary surfactant-like secretions outside the lungs and that the novel paralogue of SFTPC might facilitate extrapulmonary respiration in the absence of lungs. Heterotopic expression of the SFTPC paralogue may have contributed to the remarkable evolutionary radiation of lungless salamanders, which account for more than two thirds of urodele species alive today.


Assuntos
Adaptação Biológica/fisiologia , Proteínas de Anfíbios/genética , Respiração/genética , Urodelos/fisiologia , Adaptação Biológica/genética , Proteínas de Anfíbios/metabolismo , Animais , Evolução Molecular , Análise de Sequência de DNA , Tensoativos/metabolismo , Urodelos/genética
20.
Zoolog Sci ; 35(5): 427-435, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30298788

RESUMO

The Japanese clouded salamander (Hynobius nebulosus) is a lentic-breeding species distributed throughout western Japan. Threats, such as habitat loss, have led to it being categorized as a vulnerable species. To explore the phylogeographic features and population differentiation among clouded salamanders in Shiga prefecture, we analyzed sequences of the mitochondrial cytochrome b gene. DNA samples were collected from 29 distinct breeding sites, and 53 cytochrome b haplotypes were identified. On the basis of comparison of the composition and frequency of haplotypes in each breeding site, salamanders in each habitat appeared to have distinct characteristics. Significant genetic differentiation was observed in 93.3% of possible pairs of habitats in Shiga prefecture, and 67.7% of habitat pairs within the same locality were found to be significantly different. These results suggest that the salamanders' poor locomotion combined with topographic effects may have contributed to the diversity of locally distributed salamanders in Shiga. Phylogenetic analysis showed that haplotypes of H. nebulosus in Shiga can be divided into five groups (the Nagahama-Maibara group, Otsu group, Konan group 1, Konan group 2, and Takashima group), each with a distinct geographical distribution. Haplotypes of the Otsu group, however, were exceptionally widely distributed. The results of the present study will contribute to the future of H. nebulosus conservation management in Shiga.


Assuntos
Variação Genética , Urodelos/genética , Distribuição Animal , Animais , Citocromos b/genética , DNA Mitocondrial/genética , Espécies em Perigo de Extinção , Japão , Filogenia , Filogeografia
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